Four-line large-span tunnel cable-arch combined primary support structure

Abstract

The invention discloses a four-line large-span tunnel cable-arch combined primary support structure, which can effectively control the problems that the arch top of the four-line large-span tunnel settles and the support cracks, ensures the stability and safety of the construction and operation of the tunnel, simultaneously reduces the temporal support in construction, has less procedure interference and rapid construction speed, and is beneficial for the operation of large-scale machinery. The structure comprises a sprayed concrete layer (10) covered on a surrounding rock and whole ring steel frames (20) arranged along a tunnel excavation direction at intervals, and a system anchor bar arched on the surrounding rock along an arch wall face, wherein, the whole ring steel frames (20) are embedded in the sprayed concrete layer (10); a first group of prestressing force anchor cables (31) which are anchored on the surrounding rock, and are connected with the whole ring steel frames (20) are arranged at the connection part of a tunnel arch part steel frame and a temporary vertical support along the tunnel excavation direction at intervals; and a second group of prestressing force anchor cables (32) and a third group of prestressing force anchor cables (33) which are anchored on the surrounding rock and connected with the whole ring steel frames (20) are respectively arranged on the side wall part and close to an arch foot along the tunnel excavation direction.

Description

technical field [0001] The invention relates to an initial support structure of a tunnel, in particular to an initial support structure of a four-line long-span tunnel in soft rock. Background technique [0002] After entering the 21st century, my country's railway construction has developed rapidly, with the rapid and large-scale construction of high-speed railways in mountainous areas. Due to the constraints of many factors such as large curve radius, complex terrain and geological conditions, and high environmental protection requirements, it is extremely difficult to set up station conditions in some sections along the railway. Therefore, in order to improve the freedom of route selection and station establishment for building high-speed railways in difficult and dangerous mountainous areas, make the layout of mountainous stations more flexible, and ensure station functions more easily, more and more super-long-span four-line station tunnels will be built. [0003] The ...

AI Technical Summary

Problems solved by technology

[0004] For the four-line long-span tunnel in soft rock formation, the traditional primary support structure (system bolt + steel frame + sprayed concrete) is adopted. On the one hand, due to the large span and soft rock, the deformation after excavation is not suitable for control

It is characterized by large amount of deformation, fast deformation, long duration, easy cracking of support, and even collapse caused by instability; on the other hand, in order to ensure safety, it is necessary to limit the step length of support removal during construction, and adopt measures such as jumping and demolition , resulting in inflexible construction and narrow working face

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